To provide a higher transmission bandwidth, a CA (carrier aggregation) technology is put forward in the prior art. The CA technology is a technology of aggregating spectrums of at least two carriers. In the CA technology, spectrums of component carriers may be contiguous continuous spectrums, or may be noncontiguous spectrums in a same band or even discontinuous spectrums in different bands. By using the CA technology, a UE (user equipment) in an LTE-A (Long Term Evolution-Advanced) system can use multiple component carriers simultaneously according to its capability and service requirement to transmit or receive data.
In a technology in which carriers of multiple base stations are used to perform aggregation (for example, one UE may be connected to two base stations), when transmission times of downlink channels (downlink transmission time, for short) of two base stations are not synchronous, as shown in FIG. 1, downlink transmission times of cells Cell 1 and Cell 2 are not synchronous, which makes uplink transmission times of the Cell 1 and the Cell 2 be not synchronous; consequently, a subframe i (a subframe numbered i) corresponding to an uplink channel of the Cell 1 overlaps a subframe j (a subframe numbered j) and a subframe j+1 (a subframe numbered j+1) that are corresponding to an uplink channel of the Cell 2, where the Cell 1 and the Cell 2 belong to different base stations. A transmission start moment of the subframe j is earlier than a transmission start moment of the subframe i, and a transmission start moment of the subframe j+1 is later than the transmission start moment of the subframe i, where i, j, and j+1 are subframe numbers. When i, j, or j+1 is out of a range 0˜9, the subframe number is i mod 10, j mod 10, or (j+1)mod 10. When the UE decides a channel power of a subframe (assumed as the subframe i), it needs to consider power allocation of uplink channels of two subframes (assumed as the subframe j and the subframe j+1) of a cell covered by another base station, where the two subframes overlap the subframe i. That is, it is ensured that a sum of transmit powers of multiple channels in any time segment cannot exceed a maximum transmit power of the UE in the time segment. Before a downlink subframe i−4 ends, the UE has learned uplink channel information of the subframe i and the subframe j, but still cannot learn uplink channel information of the subframe j+1. Generally, a subframe i+n represents an nth subframe following the subframe i, where n is a positive integer; and a subframe i−n represents an nth subframe previous to the subframe where n is a positive integer. When the UE does not support reduction of processing time for deciding a transmit power of an uplink channel of the subframe i (that is, time for waiting for learning an uplink channel of the subframe j+1 cannot be subtracted), unless absence of an uplink channel on the subframe j+1 is learned according to semi-statically configured information, that is, transmission of an uplink channel is possible, the UE reserves a guaranteed power for a base station or a cell group in which the subframe j+1 is located, so as to decide the transmit power of the uplink channel, which is to be allocated to the subframe i. The guaranteed power is a semi-static power value, and the semi-static power value is a power configured by using higher layer signaling such as RRC (Radio Resource Control) signaling. Generally, one guaranteed power is available for each base station or cell group.
In the prior art, a guaranteed power is preset for the base station or the cell group in which the subframe j+1 is located, without considering actual transmit power allocation of the uplink channel of the subframe j+1; then the transmit power, which is to be allocated to the subframe i, of the corresponding uplink channel is decided according to the guaranteed power. However, when the guaranteed power is less than a transmit power, which is actually required by the subframe j+1, of the uplink channel, receiving performance of an uplink channel of the UE in a base station of a cell in which the UE is located is affected, where the uplink channel is an uplink channel in which the subframe j+1 is located. When the guaranteed power is greater than a transmit power, which is actually required by the subframe j+1, of the uplink channel, and consequently, the transmit power, which is allocated to the subframe i, of the uplink channel is less than an actual transmit power of the uplink channel of the subframe i, receiving performance of an uplink channel of the UE in a base station of a cell in which the UE is located is affected, where the uplink channel is an uplink channel in which the subframe i is located. That is, when the reserved transmit power (guaranteed power) of the uplink channel is improper, the receiving performance of the uplink channel of the UE in the base station of the cell in which the UE is located is affected.